A BOBBIN CAPABLE OF RELIABLY INSULATING A FIRST COIL FROM A SECOND COIL

Abstract: In a bobbin having a first board (55) and a second board (57) opposed to the first board, first and second sleeves (59, 61) are integral with the first and the second boards, respectively. The first sleeve is inserted in the second sleeve. A divider sleeve (63) is integrated with the second board with the divider sleeve surrounding the second sleeve and a first perforation of the second board. The divider sleeve is interposed between the first and the second board with the divider sleeve surrounding the first sleeve and with the divider sleeve welded or glued to the first board. First-set and second-set connectors (51, 53) are fixed to the bobbin. A first coil (43) is attached around the divider sleeve and is connected to the first-set connectors. A second coil (45) is attached around the second sleeve and is connected to the second-set connectors through the first perforation. The divider sleeve may be integral with the first board. First and second coupling arms (97, 99) may be integral with the first board and may pass second and third perforations of the second board with the coupling peak portions of the first and the second coupling arms brought into contact with a surface of the second board. The first and the second coupling arms may pass first and second ditches of the second board. In this event, the divider sleeve is brought into contact with the first or the second board.

Description: A BOBBIN CAPABLE OF RELIABLY INSULATING A FIRST COIL FROM A SECOND COIL Background of the Invention: This invention relates to a bobbin and to a transformer which comprises a bobbin under consideration. A conventional bobbin comprises a sleeve, a plurality of divider plates, and first and second end plates. The sleeve has a sleeve internal surface which defines a sleeve perforation. The divider plates are attached to the sleeve with a space left between two adjacent ones of the divider plates and with the divider plates perpendicular to the sleeve. The first and the second end plates are attached to side ends of the sleeve with a space left between one of the divider plates and each of the first and the second end plates. A conventional transformer comprises the bobbin, first and second coils attached to the bobbin, a magnetic core attached to the bobbin, and first-set and second-set connectors. The first and the second coils are attached around the sleeve between the divider plates. The first and the second coils are connected to the first-set and the second-set converters, respectively. In the bobbin and the transformer, it is hardly possible to reliably insulate the first coil from the second coil by the divider plates. This is because the divider plates do not surround the first coil or the second coil. Also, inasmuch as the divider plates are perpendicular to the sleeve and are high in height, the bobbin and the transformer are high in height. Summary of the Invention: It is therefore an object of this invention to provide a bobbin or a transformer which is capable of reliably insulating a first coil from a second coil. it is another object of this invention to provide a bobbin or a transformer which is low in height. Other objects of this invention will become clear as the description proceeds. According to a first aspect of this invention, there is provided a bobbin which comprises (A) a first board having a first board main surface and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface and second and third board internal surfaces which define second and third board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; and (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the second board with the divider sleeve surrounding the second sleeve and the third board perforation and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the first sleeve, the divider sleeve being welded to the first board main surface. According to a second aspect of this invention, there is provided a bobbin which comprises (A) a first board having a first board main surface and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface and second and third board internal surfaces which define second and third board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; and (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the second board with the divider sleeve surrounding the second sleeve and the third board perforation and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the first sleeve, the divider sleeve being glued to the first board main surface. According to a third aspect of this invention, there is provided a bobbin which comprises (A) a first board having a first board main surface and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface and second and third board internal surfaces which define second and third board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; and (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the first board with the divider sleeve surrounding the first sleeve and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the second sleeve and the third board perforation, the divider sleeve being welded to the second board main surface. According to a fourth aspect of this invention, there is provided a bobbin which comprises (A) a first board having a first board main surface and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface and second and third board internal surfaces which define second and third board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; and (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the first board with the divider sleeve surrounding the first sleeve and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the second sleeve and the third board perforation, the divider sleeve being glued to the second board main surface. According to a fifth aspect of this invention, there is provided a bobbin which comprises (A) a first board having a first board main surface and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, and second, third, fourth, and fifth board internal surfaces which define second, third, fourth, and fifth board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; (E) a divider sleeve having ε, divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the second board with the divider sleeve surrounding the second sleeve and the third board perforation and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the first sleeve and is brought into contact with the first board main surface; and (F) first and second coupling arms having first and second coupling peak portions, the first and the second coupling arms being integral with the first board, the first and the second coupling arms passing through the fourth and the fifth board perforations with the first and the second coupling peak portions brought into contact with the second board subsidiary surface. According to a sixth aspect of this invention, there is provided a bobbin which comprises (A) a first board having a first board main surface and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, and second, third, fourth, and fifth board internal surfaces which define second, third, fourth, and fifth board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the first board with the divider sleeve surrounding the first sleeve and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the second sleeve and the third board perforation and is brought into contact with the second board main surface; and (F) first and second coupling arms having first and second coupling peak portions, the first and the second coupling arms being integral with the first board, the first and the second coupling arms passing through the fourth and the fifth board perforations with the first and the second coupling peak portions brought into contact with the second board subsidiary surface. According to a seventh aspect of this invention, there is provided a bobbin which comprises (A) a first board having a first board main surface and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, second and third board internal surfaces which define second and third board perforations, and first and second ditch surfaces which reach from the second board main surface to the second board subsidiary surface and define first and second ditches; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the second board with the divider sleeve surrounding the second sleeve and the third board perforation and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the first sleeve and is brought into contact with the first board main surface; and (F) first and second coupling arms having first and second coupling peak portions, the first and the second coupling arms being integral with the first board, the first and the second coupling arms passing through the first and the second ditches with the first and the second coupling peak portions brought into contact with the second board subsidiary surface. According to an eighth aspect of this invention, there is provided a bobbin which comprises (A) a first board having a first board main surface and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations, and first and second ditch surfaces which reach from the second board main surface to the second board subsidiary surface and define first and second ditches; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; and (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the first board with the divider sleeve surrounding the first sleeve and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the second sleeve and the third board perforation and is brought into contact with the second board main surface; and (F) first and second coupling arms having first and second coupling peak portions, the first and the second coupling arms being integral with the first board, the first and the second coupling arms passing through the first and the second ditches with the first and the second coupling peak portions brought into contact with the second board subsidiary surface. According to a ninth aspect of this invention, there is provided a transformer which comprises a bobbin, first and second coils attached to the bobbin, first and second magnetic cores attached to the bobbin, and first-set and second-set connectors fixed to the bobbin, wherein: the bobbin comprises (A) a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; and (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the second board with the divider sleeve surrounding the second sleeve and the third board perforation and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the first sleeve, the divider sleeve being welded to the first board main surface; the first coil being attached around the divider sleeve and being connected to the first-set connectors, the second coil being attached around the second sleeve and being connected to the second-set connectors through the third board perforation; the first magnetic core having a first leg, the first magnetic core being brought into contact with the first board subsidiary surface with the first leg inserted in the first sleeve perforation, the second magnetic core having a second leg, the second magnetic core being brought into contact with the second board subsidiary surface with the second leg inserted in the first sleeve perforation and brought into contact with the first leg. According to a tenth aspect of this invention, there is provided a transformer which comprises a bobbin, first and second coils attached to the bobbin, first and second magnetic cores attached to the bobbin, and first-set and second-set connectors fixed to the bobbin, wherein the bobbin comprises (A) a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; (B) a second board having a second board mair surface opposed to the first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; and (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the second board with the divider sleeve surrounding the second sleeve and the third board perforation and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the first sleeve, the divider sleeve being glued to the first board main surface; the first coil being attached around the divider sleeve and being connected to the first-set connectors, the second coil being attached around the second sleeve and being connected to the second-set connectors through the third board perforation; the first magnetic core having a first leg, the first magnetic core being brought into contact with the first board subsidiary surface with the first leg inserted in the first sleeve perforation, the second magnetic core having a second leg, the second magnetic core being brought into contact with the second board subsidiary surface with the second leg inserted in the first sleeve perforation and brought into contact with the first leg. According to an eleventh aspect of this invention, there is provided a transformer which comprises a bobbin, first and second coils attached to the bobbin, first and second magnetic cores attached to the bobbin, and first-set and second-set connectors fixed to the bobbin, wherein the bobbin comprises (A) a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; and (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the first board with the divider sleeve surrounding the first sleeve and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the second sleeve and the third board perforation, the divider sleeve being welded to the second board main surface; the first coil being attached around the divider sleeve and being connected to the first-set connectors, the second coil being attached around the second sleeve and being connected to the second-set connectors through the third board perforation; the first magnetic core having a first leg, the first magnetic core being brought into contact with the first board subsidiary surface with the first leg inserted in the first sleeve perforation, the second magnetic core having a second leg, the second magnetic core being brought into contact with the second board subsidiary surface with the second leg inserted in the first sleeve perforation and brought into contact with the first leg. According to a twelfth aspect of this invention, there is provided a transformer which comprises a bobbin, first and second coils attached to the bobbin, first and second magnetic cores attached to the bobbin, and first-set and second-set connectors fixed to the bobbin, wherein the bobbin comprises (A) a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; and (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the first board with the divider sleeve surrounding the first sleeve and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the second sleeve and the third board perforation, the divider sleeve being glued to the second board main surface; the first coil being attached around the divider sleeve and being connected to the first-set connectors, the second coil being attached around the second sleeve and being connected to the second-set connectors through the third board perforation; the first magnetic core having a first leg, the first magnetic core being brought into contact with the first board subsidiary surface with the first leg inserted in the first sleeve perforation, the second magnetic core having a second leg, the second magnetic core being brought into contact with the second board subsidiary surface with the second leg inserted in the first sleeve perforation and brought into contact with the first leg. According to a thirteenth aspect of this invention, there is provided a transformer which comprises a bobbin, first and second coils attached to the bobbin, first and second magnetic cores attached to the bobbin, and first-set and second-set connectors fixed to the bobbin, wherein the bobbin comprises (A) a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, and second, third, fourth, and fifth board internal surfaces which define second, third, fourth, and fifth board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the second board with the divider sleeve surrounding the second sleeve and the third board perforation and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the first sleeve and is brought into contact with the first board main surface; and (F) first and second coupling arms having first and second coupling peak portions, the first and the second coupling arms being integral with the first board, the first and the second coupling arms passing through the fourth and the fifth board perforations with the first and the second coupling peak portions brought into contact with the second board subsidiary surface; the first coil being attached around the divider sleeve and being connected to the first-set connectors, the second coil being attached around the second sleeve and being connected to the second-set connectors through the third board perforation;- the first magnetic core having a first leg, the first magnetic core being brought into contact with the first board subsidiary surface with the first leg inserted in the first sleeve perforation, the second magnetic core having a second leg, the second magnetic core being brought into contact with the second board subsidiary surface with the second leg inserted in the first sleeve perforation and brought into contact with the first leg. According to a fourteenth aspect of this invention, there is provided a transformer which comprises a bobbin, first and second coils attached to the bobbin, first and second magnetic cores attached to the bobbin, and first-set and second-set connectors fixed to the bobbin, wherein the bobbin comprises (A) a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, and second, third, fourth, and fifth board internal surfaces which define second, third, fourth, and fifth board perforations; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the first board with the divider sleeve surrounding the first sleeve and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the second sleeve and the third board perforation and is brought into contact with the second board main surface; first and second coupling arms having first and second coupling peak portions, the first and the second coupling arms being integral with the first board, the first and the second coupling arms passing through the fourth and the fifth board perforations with the first and the second coupling peak portions brought into contact with the second board subsidiary surface; the first coil being attached around the divider sleeve and being connected to the first-set connectors, the second coil being attached around the second sleeve and being connected to the second-set connectors through the third board perforation; the first magnetic core having a first leg, the first magnetic core being brought into contact with the first board subsidiary surface with the first leg inserted in the first sleeve perforation, the second magnetic core having a second leg, the second magnetic core being brought into contact with the second board subsidiary surface with the second leg inserted in the first sleeve perforation and brought into contact with the first leg. According to a fifteenth aspect of this invention, there is provided a transformer which comprises a bobbin, first and second coils attached to the bobbin, first and second magnetic cores attached to the bobbin, and first-set and second-set connectors fixed to the bobbin, wherein the bobbin comprises (A) a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, second and third board internal surfaces which define second and third board perforations, and first and second ditch surfaces which reach from the second board main surface to the second board subsidiary surface and define first and second ditches; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the second board with the divider sleeve surrounding the second sleeve and the third board perforation and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the first sleeve and is brought into contact with the first board main surface; and (F) first and second coupling arms having first and second coupling peak portions, the first and the second coupling arms being integral with the first board, the first and the second coupling arms passing through the first and the second ditches with the first and the second coupling peak portions brought into contact with the second board subsidiary surface; the first coil being attached around the divider sleeve and being connected to the first-set connectors, the second coil being attached around the second sleeve and being connected to the second-set connectors through the third board perforation; the first magnetic core having a first leg, the first magnetic core being brought into contact with the first board subsidiary surface with the first leg inserted in the first sleeve perforation, aid second magnetic core having a second leg, the second magnetic core being brought into contact with the second board subsidiary surface with the second leg inserted in the first sleeve perforation and brought into contact with the first leg. According to a sixteenth aspect of this invention, there is provided a transformer which comprises a bobbin, first and second coils attached to the bobbin, first and second magnetic cores attached to the bobbin, and first-set and second-set connectors fixed to the bobbin, wherein the bobbin comprises (A) a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; (B) a second board having a second board main surface opposed to the first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations, and first and second ditch surfaces which reach from the second board main surface to the second subsidiary surface and define first and second ditches; (C) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, the first sleeve being integral with the first board with the first sleeve perforation associated with the first board perforation; (D) a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, the second sleeve being integral with the second board with the second sleeve perforation associated with the second board perforation, the second board and the second sleeve perforations receiving the first sleeve; (E) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, the divider sleeve being integral with the first board with the divider sleeve surrounding the first sleeve and with the divider sleeve interposed between the first and the second board main surfaces so that the divider sleeve surrounds the second sleeve and the third board perforation and is brought into contact with the second board main surface; and (F) first and second coupling arms having first and second coupling peak portions, the first and the second coupling arms being integral with the first board, the first and the second coupling arms passing through the first and the second ditches with the first and the second coupling peak portions brought into contact with the second board subsidiary surface; the first coil being attached around the divider sleeve and being connected to the first-set connectors, the second coil being attached around the second sleeve and being connected to the second-set connectors through the third board perforation; the first magnetic core having a first leg, the first magnetic core being brought into contact with the first board subsidiary surface with the first leg inserted in the first sleeve perforation, the second magnetic core having a second leg, the second magnetic core being brought into contact with the second board subsidiary surface with the second leg inserted in the first sleeve perforation and brought into contact with the first leg. Brief Description of the Drawing: Fig. 1 is a perspective view of a conventional bobbin; Fig. 2 is a perspective view of a conventional transformer; Fig. 3 is an exploded perspective view of a transformer according to a first embodiment of this invention; Fig. 4 is a perspective view of the transformer illustrated in Fig. 3; Fig. 5 is a partial sectional view of the transformer illustrated in Fig. 4; Fig. 6 is an exploded sectional view of the transformer illustrated in Fig. 4; Fig. 7 is a sectional view taken along a line 7-7 in Fig. 4; Fig. 8 is an exploded perspective view of a transformer according to a second embodiment of this invention; Fig. 9 is an exploded sectional view of the transformer illustrated in Fig. 8; Fig. 10 is an exploded perspective view of a transformer according to a third embodiment of this invention; and Fig. 11 is a perspective view of the transformer illustrated in Fig. 10. Description of the Preferred Embodiment: Referring to Fig. 1, a conventional bobbin will first be described for a better understanding of this invention. The conventional bobbin comprises a sleeve 21, a plurality of divider plates 23, and first and second end plates 25 and 27. The sleeve 21 has a sleeve internal surface 28 which defines a sleeve perforation. The divider plates 23 are attached to the sleeve with a space left between two adjacent ones of the divider plates 23 and with the divider plates 23 perpendicular to the sleeve 21. The first and the second end plates 25 and 27 are attached to side ends of the sleeve 21 with a space left between one of the divider plates 23 and each of the first and the second end plates 25 and 27. Referring to Fig. 2, a conventional transformer will be described for a better understanding of this invention. Similar parts are designated by like reference numerals. The conventional transformer comprises the bobbin, first and second coils 29 and 31 attached to the bobbin, a magnetic core (not shown) attached to the bobbin, and first-set and second-set connectors 33 and 35 fixed to the bobbin. The first and the second coils 29 and 31 are attached around the sleeve 21 between the divider plates 23. The first and the second coils 29 and 31 are connected to the first-set and the second-set connectors 33 and 35, respectively. In the bobbin and the transformer, inasmuch as the divider plates 23 do not surround the first coil 29 or the second coil 31, it is hardly possible to reliably insulate the first coil 29 from the second coil 31 by the divider plates 23. Also, inasmuch as the divider plates 23 are perpendicular to the sleeve 21 and are high in height, the bobbin and the transformer are high in hei : ' . ~_ . Referring to Figs. 3 to 7, the description will proceed to a transformer according to a first embodiment of this invention. The transformer comprises a bobbin 41, first and second coils 43 and 45 attached to the bobbin 41, first and second magnetic cores 47 and 49 attached to the bobbin 41, and first-set and second-set connectors 51 and 53 fixed to the bobbin 41. The bobbin 41 is made of insulating material. The bobbin 41 comprises first and second boards 55 and 57, first and second sleeves 59 and 61, and a divider sleeve 63. The first board 55 has a first board main surface 65, a first board subsidiary surface 67, and a first board internal surface 69 which defines a first board perforation. The second board 57 has a second board main surface 71 opposed to the first board main surface 65, a second board subsidiary surface 73, and second and third board internal surfaces 75 and 77 which define second and third board perforations. The first sleeve 59 has a first sleeve internal surface 79 which defines a first sleeve perforation. The first sleeve 59 is integral with the first board 55 with the first sleeve perforation associated with the first board perforation. The second sleeve 61 has a second sleeve internal surface 81 which defines a second sleeve perforation. The second sleeve 61 is integral with the second board 57 with the second sleeve perforation associated with the second board perforation. The second board and the second sleeve perforations receive the first sleeve 59. The divider sleeve 63 has a divider sleeve internal surface 83 which defines a divider sleeve perforation. The divider sleeve 63 is integral with the second board 57 with the divider sleeve 63 surrounding the second sleeve 61 and the third board perforation and with the divider sleeve 63 interposed between the first and the second board main surfaces 65 and 71 so that the divider sleeve 63 surrounds the first sleeve 59. The divider sleeve 63 is welded to the first board main surface 65. The divider sleeve 63 may be glued to the first board main surface 65. The first coil 43 is attached around the divider sleeve 63 and is connected to the first-set connectors 51. The second coil 45 is attached around the second sleeve 61 and is connected to the second-set connectors 53 through the third board perforation. The first magnetic core 47 has a first leg 85. The first magnetic core 47 is brought into contact with the first board subsidiary surface 67 with the first leg 85 inserted in the first sleeve perforation. The second magnetic core 49 has a second leg 87. The second magnetic core 9 is brought into contact with the second board subsidiary surface 73 with the second leg 87 inserted in the first sleeve perforation and brought into contact with the first leg 85. A first end portion of the first magnetic core 47 is brought into contact with a second end portion of the second magnetic core 49 and is glued to the second end portion. Referring to Figs. 8 and 9, the description will proceed to a transformer according to a second embodiment of this invention. The transformer comprises similar parts designated by like reference numerals. The divider sleeve 63 is integral with the first board 55 with the divider sleeve 63 surrounding the first sleeve 59. The divider sleeve 63 further has a contact peak portion 89 which is brought into contact with the second board main surface 71. The divider sleeve 63 surrounds the second sleeve 61 and the third board perforation. The second board 57 has first side surfaces 91 to which the first-set connectors 53 are fixed. The third board internal surface 75 reaches the first side surfaces 91. The second board 57 further has fourth and fifth board internal surfaces 93 and 95 which define fourth and fifth board perforations. First and second coupling arms 97 and 99 have first and second coupling peak portions and are integral with the first board 55. The first and the second coupling arms 97 and 99 pass through the fourth and the fifth board perforations with the first and the second peak portions brought into contact with the second board subsidiary surface 73. Referring to Figs. 10 and 11, the description will proceed to a transformer according to a third embodiment of this invention. The transformer comprises similar parts designated by like reference numerals. The second board 57 has first and second ditch surfaces 101 and 103 which reach from the second board main surface 71 to the second board subsidiary surface 73 and which define first and second ditches. The first and the second coupling arms 97 and 99 pass through the first and the second ditches with the first and the second coupling peak portions brought into contact with the second board subsidiary surface 73. The second board 57 has a locating lug 105 which is inserted in the third board perforation. While this invention has thus far been described in conjunction with a few preferred embodiments thereof. it will now be readily possible for those skilled in the art to put this invention into practice in various other manners. For example, in Figs. 3 to 7, the divider sleeve 63 may be integral with the first board 55 with the divider sleeve 63 surrounding the first sleeve 59. In this event, the divider sleeve 63 is interposed between the first and the second board main surfaces 65 and 71 so that the divider sleeve 63 surrounds the second sleeve 61 and the third board perforation. The divider sleeve 63 is welded or glued to the second board main surface 71. In Figs. 8 to 11, the divider sleeve 63 may be integral with the second board 57 with the divider sleeve 63 surrounding the second sleeve 61 and the third board perforation. In this event, the divider sleeve 63 is interposed between the first and the second board main surfaces 65 and 71 so that the divider sleeve 63 surrounds the first sleeve 59. The divider sleeve 63 has the contact peak portion 89 which is brought into contact with the first board main surface 65. Also, the divider sleeve 63 may have not the contact peak portion 89. In this event, the divider sleeve 63 is directly brought into contact with the first or the second board main surface 65 or 71.

Claims: Claims 1. A bobbin comprising: a first board having a first board main surface and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface and second and third board internal surfaces which define second and third board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; and a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said second board with said divider sleeve surrounding said second sleeve and said third board perforation and with said divider sleeve interposed between said first and said second board main (Claim 1 continued) surfaces so that said divider sleeve surrounds said first sleeve, said divider sleeve being welded to said first board main surface. 2. A bobbin comprising: a first board having a first board main surface and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface and second and third board internal surfaces which define second and third board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; and a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said second board with said divider sleeve surrounding said second sleeve and (Claim 2 continued) said third board perforation and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said first sleeve, said divider sleeve being glued to said first board main surface. 3. A bobbin comprising: a first board having a first board main surface and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface and second and third board internal surfaces which define second and third board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; and a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said (Claim 3 continued) divider sleeve being integral with said first board with said divider sleeve surrounding said first sleeve and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said second sleeve and said third board perforation, said divider sleeve being welded to said second board main surface. 4. A bobbin comprising: a first board having a first board main surface and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface and second and third board internal surfaces which define second and third board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; and (Claim 4 continued) a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said first board with said divider sleeve surrounding said first sleeve and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said second sleeve and said third board perforation, said divider sleeve being glued to said second board main surface. 5. A bobbin comprising: a first board having a first board main surface and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, and second, third, fourth, and fifth board internal surfaces which define second, third, fourth, and fifth board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said (Claim 5 continued) second board perforation, said second board and said second sleeve perforations receiving said first sleeve; a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said second board with said divider sleeve surrounding said second sleeve and said third board perforation and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said first sleeve and is brought into contact with said first board main surface; and first and second coupling arms having first and second coupling peak portions, said first and said second coupling arms being integral with said first board, said first and said second coupling arms passing through said fourth and said fifth board perforations with said first and said second coupling peak portions brought into contact with said second board subsidiary surface. 6. A bobbin as claimed in Claim 5, said divider sleeve further having a contact peak portion which is brought into contact with said first board main surface. 7. A bobbin comprising: a first board having a first board main surface and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board (Claim 7 continued) subsidiary surface, and second, third, fourth, and fifth board internal surfaces which define second, third, fourth, and fifth board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said first board with said divider sleeve surrounding said first sleeve and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said second sleeve and said third board perforation and is brought into contact with said second board main surface; and first and second coupling arms having first and second coupling peak portions, said first and said second coupling arms being integral with said first board, said first and said second coupling arms passing through said (Claim 7 twice continued) fourth and said fifth board perforations with said first and said second coupling peak portions brought into contact with said second board subsidiary surface. 8. A bobbin as claimed in Claim 7, said divider sleeve further having a contact peak portion which is brought into contact with said second board main surface. 9. A bobbin comprising: a first board having a first board main surface and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, second and third board internal surfaces which define second and third board perforations, and first and second ditch surfaces which reach from said second board main surface to said second board subsidiary surface and define first and second ditches; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said (Claim 9 continued) second board perforation, said second board and said second sleeve perforations receiving said first sleeve; a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said second board with said divider sleeve surrounding said second sleeve and said third board perforation and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said first sleeve and is brought into contact with said first board main surface; and first and second coupling arms having first and second coupling peak portions, said first and said second coupling arms being integral with said first board, said first and said second coupling arms passing through said first and said second ditches with said first and said second coupling peak portions brought into contact with said second board subsidiary surface. 10. A bobbin as claimed in Claim 9, said divider sleeve further having a contact peak portion which is brought into contact with said first board main surface. 11. A bobbin comprising: a first board having a first board main surface and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board (Claim 11 continued) subsidiary surface, and second and third board internal surfaces which define second and third board perforations, and first and second ditch surfaces which reach from said second board main surface to said second board subsidiary surface and define first and second ditches; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; and a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said first board with said divider sleeve surrounding said first sleeve and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said second sleeve and said third board perforation and is brought into contact with said second board main surface; and (Claim 11 twice continued) first and second coupling arms having first and second coupling peak portions, said first and said second coupling arms being integral with said first board, said first and said second coupling arms passing through said first and said second ditches with said first and said second coupling peak portions brought into contact with said second board subsidiary surface. 12. A bobbin as claimed in Claim 11, said divider sleeve further having a contact peak portion which is brought into contact with said second board main surface. 13. A transformer comprising a bobbin, first and second coils attached to said bobbin, first and second magnetic cores attached to said bobbin, and first-set and second-set connectors fixed to said bobbin, wherein: said bobbin comprises: a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with (Claim 13 continued) said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; and a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said second board with said divider sleeve surrounding said second sleeve and said third board perforation and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said first sleeve, said divider sleeve being welded to said first board main surface; said first coil being attached around said divider sleeve and being connected to said first-set connectors, said second coil being attached around said second sleeve and being connected to said second-set connectors through said third board perforation; said first magnetic core having a first leg, said first magnetic core being brought into contact with said first board subsidiary surface with said first leg inserted in said first sleeve perforation, said second (Claim 13 twice continued) magnetic core having a second leg, said second magnetic core being brought into contact with said second board subsidiary surface with said second leg inserted in said first sleeve perforation and brought into contact with said first leg. 14. A transformer comprising a bobbin, first and second coils attached to said bobbin, first and second magnetic cores attached to said bobbin, and first-set and second-set connectors fixed to said bobbin, wherein: said bobbin comprises: a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said (Claim 14 continued) second board perforation, said second board and said second sleeve perforations receiving said first sleeve; and a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said second board with said divider sleeve surrounding said second sleeve and said third board perforation and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said first sleeve, said divider sleeve being glued to said first board main surface; said first coil being attached around said divider sleeve and being connected to said first-set connectors, said second coil being attached around said second sleeve and being connected to said second-set connectors through said third board perforation; said first magnetic core having a first leg, said first magnetic core being brought into contact with said first board subsidiary surface with said first leg inserted in said first sleeve perforation, said second magnetic core having a second leg, said second magnetic core being brought into contact with said second board subsidiary surface with said second leg inserted in said first sleeve perforation and brought into contact with said first leg. 15. A transformer comprising a bobbin, first and second coils attached to said bobbin, first and second magnetic cores attached to said bobbin, and first-set and second-set connectors fixed to said bobbin, wherein: said bobbin comprises: a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; and a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said first board with (Claim 15 continued) said divider sleeve surrounding said first sleeve and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said second sleeve and said third board perforation, said divider sleeve being welded to said second board main surface; said first coil being attached around said divider sleeve and being connected to said first-set connectors, said second coil being attached around said second sleeve and being connected to said second-set connectors through said third board perforation; said first magnetic core having a first leg, said first magnetic core being brought into contact with said first board subsidiary surface with said first leg inserted in said first sleeve perforation, said second magnetic core having a second leg, said second magnetic core being brought into contact with said second board subsidiary surface with said second leg inserted in said first sleeve perforation and brought into contact with said first leg. 16. A transformer comprising a bobbin, first and second coils attached to said bobbin, first and second magnetic cores attached to said bobbin, and first-set and second-set connectors fixed to said bobbin, wherein: said bobbin comprises: a first board having a first board main surface, a first board subsidiary surface, and a first board (Claim 16 continued) internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; and a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said first board with said divider sleeve surrounding said first sleeve and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said second sleeve and said third board perforation, said divider sleeve being glued to said second board main surface; (Claim 16 twice continued) said first coil being attached around said divider sleeve and being connected to said first-set connectors, said second coil being attached around said second sleeve and being connected to said second-set connectors through said third board perforation; said first magnetic core having a first leg, said first magnetic core being brought into contact with said first board subsidiary surface with said first leg inserted in said first sleeve perforation, said second magnetic core having a second leg, said second magnetic core being brought into contact with said second board subsidiary surface with said second leg inserted in said first sleeve perforation and brought into contact with said first leg. 17. A transformer comprising a bobbin, first and second coils attached to said bobbin, first and second magnetic cores attached to said bobbin, and first-set and second-set connectors fixed to said bobbin, wherein: said bobbin comprises: a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, and second, third, fourth, and fifth board internal surfaces which define second, third, fourth, and fifth board perforations; (Claim 17 continued) a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said second board with said divider sleeve surrounding said second sleeve and said third board perforation and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said first sleeve and is brought into contact with said first board main surface; and first and second coupling arms having first and second coupling peak portions, said first and said second coupling arms being integral with said first board, said first and said second coupling arms passing through said fourth and said fifth board perforations with said first and said second coupling peak portions brought into contact with said second board subsidiary surface; (Claim 17 twice continued) said first coil being attached around said divider sleeve and being connected to said first-set connectors, said second cc .1 being attached around said second sleeve and being connected to said second-set connectors through said third board perforation; said first magnetic core having a first leg, said first magnetic core being brought into contact with said first board subsidiary surface with said first leg inserted in said first sleeve perforation, said second magnetic core having a second leg, said second magnetic core being brought into contact with said second board subsidiary surface with said second leg inserted in said first sleeve perforation and brought into contact with said first leg. 18. A transformer as claimed in Claim 17, said divider sleeve further having a contact peak portion which is brought into contact with said first board main surface. 19. A transformer comprising a bobbin, first and second coils attached to said bobbin, first and second magnetic cores attached to said bobbin, and first-set and second-set connectors fixed to said bobbin, wherein: said bobbin comprises: a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; (Claim 19 continued) a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, and second, third, fourth, and fifth board internal surfaces which define second, third, fourth, and fifth board perforations; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said first board with said divider sleeve surrounding said first sleeve and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said second sleeve and said third board perforation and is brought into contact with said second board main surface; first and second coupling arms having first and second coupling peak portions, said first and said second (Claim 19 twice continued) coupling arms being integral with said first board, said first and said second coupling arms passing through said fourth and said fifth board perforations with said first and said second coupling peak portions brought into contact with said second board subsidiary surface; said first coil being attached around said divider sleeve and being connected to said first-set connectors, said second coil being attached around said second sleeve and being connected to said second-set connectors through said third board perforation; said first magnetic core having a first leg, said first magnetic core being brought into contact with said first board subsidiary surface with said first leg inserted in said first sleeve perforation, said second magnetic core having a second leg, said second magnetic core being brought into contact with said second board subsidiary surface with said second leg inserted in said first sleeve perforation and brought into contact with said first leg. 20. A transformer as claimed in Claim 19, said divider sleeve further having a contact peak portion which is brought into contact with said second board main surface. 21. A transformer comprising a bobbin, first and second coils attached to said bobbin, first and second magnetic cores attached to said bobbin, and first-set and second-set connectors fixed to said bobbin, wherein: (Claim 21 continued) said bobbin comprises: a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, second and third board internal surfaces which define second and third board perforations, and first and second ditch surfaces which reach from said second board main surface to said second board subsidiary surface and define first and second ditches; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said second board perforation, said second board and said second sleeve perforations receiving said first sleeve; a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said second board with said divider sleeve surrounding said second sleeve and (Claim 21 twice continued) said third board perforation and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said first sleeve and is brought into contact with said first board main surface; and first and second coupling arms having first and second coupling peak portions, said first and said second coupling arms being integral with said first board, said first and said second coupling arms passing through said first and said second ditches with said first and said second coupling peak portions brought into contact with said second board subsidiary surface; said first coil being attached around said divider sleeve and being connected to said first-set connectors, said second coil being attached around said second sleeve and being connected to said second-set connectors through said third board perforation; said first magnetic core having a first leg, said first magnetic core being brought into contact with said first board subsidiary surface with said first leg inserted in said first sleeve perforation, aid second magnetic core having a second leg, said second magnetic core being brought into contact with said second board subsidiary surface with said second leg inserted in said first sleeve perforation and brought into contact with said first leg. 22. A transformer as claimed in Claim 21, said divider sleeve further having a contact peak portion which is brought into contact with said first board main surface. 23. A transformer comprising a bobbin, first and second coils attached to said bobbin, first and second magnetic cores attached to said bobbin, and first-set and second-set connectors fixed to said bobbin, wherein: said bobbin comprises: a first board having a first board main surface, a first board subsidiary surface, and a first board internal surface which defines a first board perforation; a second board having a second board main surface opposed to said first board main surface, a second board subsidiary surface, and second and third board internal surfaces which define second and third board perforations, and first and second ditch surfaces which reach from said second board main surface to said second subsidiary surface and define first and second ditches; a first sleeve having a first sleeve internal surface which defines a first sleeve perforation, said first sleeve being integral with said first board with said first sleeve perforation associated with said first board perforation; a second sleeve having a second sleeve internal surface which defines a second sleeve perforation, said second sleeve being integral with said second board with said second sleeve perforation associated with said (Claim 23 continued) second board perforation, said second board and said second sleeve perforations receiving said first sleeve; a divider sleeve having a divider sleeve internal surface which defines a divider sleeve perforation, said divider sleeve being integral with said first board with said divider sleeve surrounding said first sleeve and with said divider sleeve interposed between said first and said second board main surfaces so that said divider sleeve surrounds said second sleeve and said third board perforation and is brought into contact with said second board main surface; and first and second coupling arms having first and second coupling peak portions, said first and said second coupling arms being integral with said first board, said first and said second coupling arms passing through said first and said second ditches with said first and said second coupling peak portions brought into contact with said second board subsidiary surface; said first coil being attached around said divider sleeve and being connected to said first-set connectors, said second coil being attached around said second sleeve and being connected to said second-set connectors through said third board perforation; said first magnetic core having a first leg, said first magnetic core being brought into contact with said first board subsidiary surface with said first leg inserted in said first sleeve perforation, said second (Claim 23 twice continued) magnetic core having a second leg, said second magnetic core being brought into contact with said second board subsidiary surface with said second leg inserted in said first sleeve perforation and brought into contact with said first leg. 24. A transformer as claimed in Claim 23, said divider sleeve further having a contact peak portion which is brought into contact with said second board main surface.

Inventors: OHTSUKI EIJI, OHTSUKI, EIJI
Applicants: OHTSUKI EIJI, TOKIN CORP, OHTSUKI, EIJI, TOKIN CORPORATION
Application year: 1994
Main classification: H01F27
IPC codes: H01F27